Supersensitization of photographic emulsions with benzimidazolocarbocyanine dyes



Patented Sept. 7, 1954 SUPERSENSITIZATION OF PHOTOGRAPHIC EMULSIONS WITH BENZIMIDAZOLOCAR- BOCYANINE DYES Burt H. Carroll and Jean E. Jones, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application May 28, 1953, Serial No. 358,032

17 Claims.

This invention relates to photographic emulsions containing certain chain-substituted carbocyanine dyes, and as supersensitizers therefor, certain benzimidazolocarbocyanine dyes.

It is known in the art of making photographic emulsions that certain dyes of the cyanine class alter the sensitivity of photographic emulsions of the gelatino-silver kind, When the dyes are incorporated in the emulsions. It is also known that the sensitization produced by a given dye varies somewhat With the type of emulsion in which the dye is incorporated. Furthermore, the sensitization of a given emulsion by a given dye may be altered by varying the conditions in the emulsion. For example, the sensitization may be increased by increasing the silver ion concentration or decreasing the hydrogen ion concentration (i. e. increasing the alkalinity) or both. Thus, sensitization can be increased by bathing plates, coated with aspectrally sensitized emulsion, in water or in aqueous solutions of ammonia. Such a process of altering the sensitivity of a sensitized emulsion by increasing the silver ion concentration and/or by decreasing the hydrogen ion concentration is commonly called hypersensitization Hypersensitized emulsions have generally poor keeping qualities.

We have now found a new means of altering the sensitivity in emulsions containing certain chain-substituted carbocyanine dyes. Since the conditions in the emulsion, i. e. the hydrogen ion and/ or the silver ion concentration undergo little or no change in our method, we shall designate our new method as a kind of supersensitization.

It is, therefore, an object of our invention to provide photographic emulsions containing certain chain-substituted carbocyanine dyes and, as supersensitizers therefor, certain benzimidazolocarbocyanine dyes. Another object is to provide a process for preparing these sensitized emulsions. Other objects will become apparent from a consideration of the following description and examples.

The chain-substituted carbocyanine dyes useful in practicing our invention can advantageously be represented by the following general formula:

wherein R and R1 each represents an alkyl group, such as methyl, ethyl, n-propyl, carbethoxymethyl, etc., R2 represents an alkyl group, such as methyl, ethyl, etc., an aryl group, such as phenyl, o-, m, and p-tolyl, etc., or a pyrryl group (e. g. pyrryl, indolyl, benzoindolyl, pyrrocolyl, etc.), X represents an acid radical, such as chloride, iodide, bromide, perchlorate, p-toluenesulfonate, benzenesulfonate, ethylsulfate, methylsulfate, etc., and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, e. g. a heterocyclic nucleus of the thiazole series, (e. g. thiazole, 4-methylthiazole, 4-phenylthiazole, 5-methylthiazole, 5phenylthiazole, 4,5-dimethylthiazole, 4,5-dipheny1thiazole, etc.) a heterocyclic nucleus of the benzothiazole series (e. g. benzothiazole, 4 chlorobenzothiazole, 5-chlorobenzothiazole, 6 chlorobenzothiazole, 7-chlorobenzothiazole, 4 methylbenzothiazole, -methylbenzothiazole, 6 methylbenzothiazole, 5bromobenzothiazole, 6 bromobenzothiazole, 4-phenylbenzothiazole, 5 phenylbenzothiazole, 4-methoXybenzothiazole, 5 methoxybenzothiazole, -methoxybenzothiazole, -iodobenzothiazole, -iodobenzothiazole, 4 ethoxybenzothiazole, 5ethoxybenzothiazole, 5,6-dimethoxybenzothiazole, 5-hydroxybenzothiazole, G-hydroxybenzothiazole, etc.), a heterocyclic nucleus of the naphthothiazole series (e. g. -naphthethiazole, -naphthothiazole, 7-methoXy-a-naphthothiazole, 8 methoXy-a-naphthothiazole, 5-methoxy--naphthothiazole, 5-ethoXy-a-naphthothiazole, etc), a heterocyclic nucleus of the benzoselenazole series (e. g. benzoselenazole, 5chlorobenzoselenazole, -methoxybenzoselenazole, -methoxybenzoselenazole, etc.) a heterocyclic nucleus of the naphthoselenazole series (e. g. nc-naphthoselenazole, -naphthoselenazole, etc), a heterocyclic nucleus of the benzoxazole series (e. g. benzoxazole, -hydroxybenzoxazole, 6-hydroxybenzoxazole, 5-chlorobenzoxazole, -methoxybenzoxazole, 6-methoxybenzoxazole, 5-phenylbenzoxazole, -bromobenzoxazole, ete), a heterocyclic nucleus of the naphthoxazole series (e. g. a-naphthoxazole, -naphthoxazole, etc.), a heterocyclic nucleus of the Z-quinoline series (e. g. 2-quinoline, 6-methyl-Z-quinoline, 7-methyl-2-quinoline, S-methyl- Z-quinoline, 6-ch1oro-2-quinoline, 8-chloro-2- quinoline, 4chloro 2 quinoline, 5-ethoXy-2- quinoline, 6 ethoxy-2-quinoline, '-ethoxy-Z- quinoline, 6-hydroxy-2-quinoline, 7-hydroXy-2- quinoline, -methoxy-Z-quinoline, etc.), etc.

The dyes of Formula I above wherein R2 represents a pyrryl group comprise the dyes selected from those represented by the following general formula:

wherein R, R1, Z, Z1, and X- each have the values given above, Rs represents a hydrogen atom or an alkyl group, such as methyl, ethyl, etc., Ri represents a hydrogen atom, analkyl group, such as methyl, ethyl, n-propyl,l n-amyl, n-heptyl, n-dodecyl, cyclohexyl, etc., or an. aryl group, such as phenyl, o, m, and p-tolyl, etc., and Rx and R4 together represent the non-metallic atoms necessary to complete a heterocyclic nucleus oi the pyridine series, and` Z2 represents the nonmetallic atoms necessary to complete a pyrrole nucleus (includes simple pyrrole nuclei or condensed nuclei, e. g.V indole).

The dyes representedy by Formula I above wherein R2 represents an alkylor an aryl group have been previously described in the prior art. See, for example, U. S. patents 1,934,659 (dated Novembery 7, 1933), 2,369,646 (dated February 20, 1945), 2,369,657 (dated February 20, 1945), etc. The dyes of Forumla Iabove wherein R2 represents a pyrryl group. or the dyes of Formula Ia have been previously described in. HeseltineV et al. U. S. application Serial No.267,928, led January 23, 1952.

The benzimidazolocarbocyanine dyes useful in practicing our inventioncan advantageously be represented by the following general formula:

wherein R5 and Re each represents an alkyl group, such as methyl, ethyl, allyl (vinylmethyl) etc., nrepresents a positiveV integer of from l to 2, and X1 represents an acid radical, for example, those set forth above for X. The dyes represented by Formula II can advantageously be prepared according to the methods described in Van Lare U. S. application Serial No. 339,459, iled on February 27, 1953.

According to ourv invention, We incorporate one or more of the carbocyanine dyes selected from those represented by Formulas I or Ia above with one or more of. the dyesl selected from those represented by Formula II above in a photc graphic emulsion. Our invention is partcularly directed to the ordinarily employed gelatine-silver-halide emulsions. However, our supersensitizing combinations can be employed in silver halide emulsions in which the carrier is other than gelatin, e. g., a resinous substance or cellulosic material which has no deteriorating effect on the light-sensitive materials.

The sensitizing dyes can be employed in various concentrations depending upon the effects desired. As is well known in the art, the sensitivity conferred upon an emulsion by a sensitizing dye does not increase proportionately tothe concentration of the dye in the emulsion, but rather passes through a maximum as the concentration is increased. In practicing our invention, the individual sensitizing dyes are advantageously employed in a concentration somewhat less than their optimum concentration (i. e. the concentration at which the individual dyes give greatest sensitivity). If each of the dyes in the supersensitizing combination is employed in its optimum concentration, it is possible, in certain cases that the sensitization produced by the supersensitizing combination will have passed through a maximum.

The optimum concentration of an individual sensitizing dye can be determined in a manner well known to those skilled in the art by measuring the sensitivity of a series of test portions of the same emulsion, each portion containing a different concentration of the sensitizing dye. The optimum concentration of our supersensitizing combinations can, of course, be readily determined in the same manner, by measuring the sensitivity of a series of test portions of the same emulsion, each portion containing diierent concentrations of the individual dyes in the combination. In determining the optimum concentration for the supersensitizing combination, it is advantageous to employ, at first, concentrations of the individual dyes less than their optimum concentrations. The concentrations of the individual dyes can then be increased until the optimum concentration of the supersensitizing combination is determined.

Ordinarily the optimum or near optimum concentration of the carbocyanine dyes selected from those represented by Formula I or Ia above, which we employ in practicing our invention, is of the order of from 0.025 to 0.30 g. per mol. of silver halide in the emulsion.

The carbocyanine dyes selected from those represented by Formula II above are advantageously employed in concentrations on the order of from 0.025 to 0.30 g. per mol. of silver halide in the emulsion.

Generally speaking, the ratio of concentration of the carbocyanine dye of Formula 1I to the carbocyanine dye of Formula I or Ia can vary rather widely in our combinations, e. g. from 1:20 to 1:1 (by weight) in many cases.

The methodsV of incorporating sensitizing dyes in emulsions are well known te those skilled in the art. In practicing our invention, the sensitizing dyes can be incorporated in the emulsions separately or together. It is convenient to add the dyes separately in the form of solutions in appropriate solvents. Methanol and ethanol, especially the former, have proven satisfactory as solvents for the dyes of Formulas l', Ia, and Il which we employ, although acetone has also been found to be satisfactory in certain cases. The dyes are advantageously incorporated in the nished, washed emulsions and should be uniformly distributed throughout the emulsions. The following procedure is satisfactory: Stock solutions of the sensitizing dyes desired are prepared by dissolving the dyes in appropriate solvents as described above. Then, to the iiowable gelatinesilver-halide emulsion, the desired amounts of the stock solution of one of the dyes is slowly added, while stirring the emulsion. Stirring is continued until the dye is thoroughly incoroporated in the emulsion. Then the desired amount of the stock solution of the second dye is slowly added to the emulsion, while stirring. Stirring is continued until the second dye is thoroughly incorporated. The super-sensitized emulsion can then be coated out on a suitable support, such as glass, cellulose derivative lm, resin nlm, or

paper, to a suitable thickness and allowed to dry. The details of such coating methods are well known to those skilled in the art.

The amounts of the individual sensitizing dyes actually incorporated in the emulsion will vary somewhat from dye to dye, according to the emulsion employed and according to the effect desired. The regulation and adoption of the most economical and useful proportions will be apparent to those skilled in the art upon making the ordinary observations and tests customarily employed in the art. Accordingly, the foregoing procedures and proportions are to be regarded only as illustrative. Clearly our invention is directed to any emulsion containing a combination of the aforesaid sen-sitizing dyes whereby a supersensitizing effect is obtained.

The following examples will serve to illustrate further the manner of practicing our invention. To different portions of the same batch of photographic gelatino-silver-bromiodide emulsion were added (l) a carbocyanine dye selected from those of Formulas I or Ia above and (2) a combination of the carbocyanine dye of Formula I or Ia and a carbocyanine dye selected from those represented by Formula II above. In some instances, a third coating was prepared using the same emulsion formula and adding only one of the carbocyanine dyes selected from those of Formula II. In some instances, the table will show that this third coating gave only a low speed or one too small to measure in the region transmitted by the filter designated asterisk in the table). Dill'erent emulsions were used in some of the examples, although the emulsions of each individual example were obtained from the same batch. However, the coatings of Examples 2 to 7 were obtained from the same batch of emulsion. The coatings of Examples 8 to 10 were obtained from the same batch of emulsion. The coatings of Examples l1 to 13 were obtained from the same batch of emulsion,l the coatings of Examples 14 to 16` were obtained from the same batch of emulsion, and the coatings of Examples 17 and 18 were obtained from the same batch of emulsion. The coatings of Examples 18 and 19 were obtained from the same batch of emulsion, the coatings of Examples 21 to 26 were obtained from the same batch of emulsion, the coatings of Examples 28 to 31 were obtained from the same batch of emulsion, the coatings of Examples 32 to 38 were made from the same batch of emulsion, and the coatings of Examples 39 to l12 were made from the same ,batch of emulsion. Before coating, the emulsions containing the senstizing dyes were digested for a short time in a tank maintained at 52 C. The diierent portions of emulsion were then coated on supports and exposed in the usual manner in a spectrograph and a sensitometer (Type Ib) through either a Wratten 25 lter, i. e. a filter which transmits substantially no light of Wavelength shorter than 580 mu, a Wratten 12 lter, i. e. a lter which transmits substantially no. lightof wavelength shorter than 495 mu, or a Wratten 58 lter, i. e. a lter which transmits only light of wavelengths lying between 465 and 620 mu. The following are several examples of such emulsions together With the speed (red, minus blue or green), gamma and fog obtainedafter development of the exposed emulsions in the usual manner.

Dye (g. per mole of silver halide in emulslon) {(d) dye (b) 0) {(i) dye (c) (0.08

(j) dye (a) (0.040) plus dye (g) (0.080)

{(k) 3,3'-diethyl-Q-methyselenacarbocyanine iodide (0.080). (l) dye (a) (0.040) plus dye (k) (0.080) (m) dye (k) (0.080) plus dye (c) (0.040)

(o) dye (n) (0.080) plus dye (e) (0.040) (p) dye (a) (0.080)

(q) 3,3dimethyl0-ethylthiacarbocyauine bro (r) dye (q) (0.350) plus dye (a) (0.040)

(n) 3,3'.filmen]yi-e-ethyneienaearbocyaflli1621121020080" (a) 5,5dichloro-1,1,3,3tetraethylbenzimidazoloearbocyanine iodide (0.080) (b) 5.5di0h10r033.Q-trethylthiacarbocyanino bromide (0.080)

(a) plus dye (b) (0.080)

2.18 2. 78 2.70 2.80 2. 66 2. 77 3.10 2. 58 2. 20 2. 70 2. 2. 60 2. 60 2.03 2. 87 1.86 2.07 2. 47 (s) dye (e) 2. 44 (t) dye (q) (0.080) plus dye (e) (0.040) 2.32 (u) 3.3diethyl-Q-methyloxacarbocyanine iodide (0.080) 2. 2.18 01) dye (u.) (0.080) plus dye (a) (0.040) 29. 2. 50 (2v) dye (e) (0.080) 49. 1.78 (x) 5,5diacetoxy-3,3diethyl9methylthiaoarbocyanine iodide (0.080) 30. 3.22 (y) dye (x) (0.080) plus dye (e) (0.040) 58. 2.84 (2) 5,5-diacetoxy3,3 ,9-trimethy1thiacarbocyanine iodide (0 080) 20. 3.16 (a) dye (z) (0.080) plus dye (e) (0.040) 54. 2. 06 {(b) 3,9diethyl3methyl4,5benzoxathiacarbocyanine 24. 1.86 (c) dye (b) (0.080) plus dye (e) (0.040) 7l. 2.48 (d) dye (e) (0.020) 2.34 (e) 3,3diethyl4methyl0xatbiazolocarbocyanine iodide (0.080) 3.26 .05 gf?) gy@ (e3) (((glgz) plus dye (e) (0.020) *3.08 .gg

9 ye (e l5 {(h) 9-ethyl-l.3-dimethylthia2carbocyanine iodide (0.040)` 7-3 1.68 -04 (1" dye (h) (0.040) plus dye (e) (0.020) 11.2 1.82 .05 (j) 6,6'dichlorol,1diethyl2,2carbocyanine p-toluenesulfonate (0 40) 6.5 2.72 .05 16 (k) dye (i) (0.040) plus dye (e) (0.020) 11.0 2.60 .00 (Z) 9-(l-ethyl-Z,-dimethyl-S-pyrryl)-3,3di ethylth carbocya ne iodide (0 3.8 2.32 .08 17 (mf) dyn. (e) (0.040) -05 (77') dye (l) (0.080) plus dye (e) (0.040) 4-7 2.54 .06 (0') 3-ethyl-9-(1ethyl-2,-dimethyl-S-pyrryl)-3niethyl4,5,4,5dibenzothicarbocy- 7. 6 2. 57 07 18 aninc iodide (0.080).

(11') dye (0') (0.080) plus dye (e) (0.040) 2.30 .06 (q) dye (e) (0.040) *f* 2. 72 .05 19 (r) 3,3dimethy19(2-1netl1yl-6,7benzo3-1ndo1yl)4,5,4,5dibenz0th1acarbocyanme 2.06 .05

"""" p-toluenesulfonate (0.080).

(s) dye (e) (0.080) plus dye (r) (0.080) 2.28 .07

See footnotes at end of table.

Speed Ex. Dye (g. per mole of silver halide in emulsion) Gamma Fog Dgi'lues Bed Green {(t) 3-e(thy1-3-methy10(2-methy1-3-indo1y1)-4,5,6,7-dibcnzoxacarbocyanine perchlo- 17.8 1.31 .04 rato 0.08

(u' d e t 0.080 111s d e e (0 020) 41.0 1. 51 .04 (w) e )*13 21.0 2. 4o .o4 21 (w) 3,3dimetby19(3pyrry1)thiaeatbo 0.080) 6.2 2.80 .05 (1') dye (w) '(0.080) plus dye (e) (0.040) 23.0 2. 96 .05 22 {(y') 9-(3-indo1y1)-3,3dimethylthiacarbocyanine p-toluenesulfonate (0.080). 35.0 3.38 .05 'm' (2') dye (y') (0.080) plus dyel (e) (0.040) 40.0 3.21 .06 23 (11) 3,3diethy19(3indo1yl)4,5,6,7dibenzothiadarbocyanme bromide (0.080) 36.0 3. 40 .04 l.(b") dye (0") '(0.080) plus dye (e) (0.040). l45.0 3.17 .06 24 {(c) 3,3diethy19(3indolyl)-6,7benzoth1acarbocyamue bromide (0.080). 30.0 3. 48 05 (df') dye (w) (0.080) plus dye (e) 43.0 3.17 .05 (8) 9-(2,5-dimethyl-l-phenyl-B-pyrryl)3,3'-dimethyl-4,5,fl',dibenzothiacarboeya- 16.0 3. 20 .05 25 nine iodide (0.080).

dye (e) (0.080) plus dye (e) (0.040) 33.0 3.06 .06 ,.6 0") 9-(3indolyl)3,3-dimethy1-4,5,4',5dibenzothiacarbocyanine iodide (0.080) 30.0 3. 80 .06 4 (fw) dye (gI') (0.080) plus dye (e) (0.040) 76.0 1.14 .05 (lf') dye (e) .040) .04 .27 (1")9-(1ethyl-2,5dii11ethyl3pyrry1)-3,3d1methyl4,5,4,5dibcnzoth1acarbocyamne 5. 3 2. 38 06 iodide (0.080

(k") dye (j) (0.080) plus dye (e) (0.040) 4 2.00 .06 (1) dye (e) (0.040) 04 28 (m) 3,Bldimethyl-Q-pheny1-4,5,4,5'dibenzothlacarbocyamno bromide (0.080) 8.6 3.26 .06 (11) dye (11W) (0.080) plus dye (e) (0.040) 14.0 2.08 .08 29 {(0) 3,3diethyl-Q-phenylthlacarboeyamnc iodide (0.080). 6.6 3. 2l 05 (p") dye (0) (0.080) plus dye (e) (0.04 9.0 3.08 .06 30 {(q) 9ethyl3,3dlmethy14,5,4',5dibenzosclenacarbocyanide iodide (0.080 27.0 3.10 .05 (r") dye (q") (0.080) plus dye (e) (0.0i0) L 31.0 2.86 .0G 31 (3) 3,3'-dimethyl-Q-phenyl-i,5,4,5-dibenzose1enacarb0cyanlne bromide (0.080 4.7 2.78 .05 (t) dye (3) (0.080) plus dye (e) (0.040) 8.4 2.59 .0G (UW) dye (b) .0 0) 30.0 2.28 .0G 32 (v) 5,5dicb loro1.1,3,3tetramethylbenzimidazolocarb 1, 29 ,05 (10) dye (b) (0.080) plus dye (11") (0.040) 59.0 2.17 .06 33 {(I") dye (m) (0.080) 6. 9 2.62 .07 (11") dye (m") (0.080) plus dye (v") (0.04 23.5 2. 30 .07 34 (2) dye (q) (0.08 22. 5 1. 59 .05 'o dye (q) (0.080) plus dye (1) (0 040 4&0 2-05 -05 35 {(h 3,3'-diethyl-Q-methy1-4.5'benz0Xat 2. 28 .05 (cf' I) dye (b' (0.080) plus dye (v) (0.040)- 231 -05 dye (b) (0. 0) 2. 52 .07 d (0.080) plus dye (v (30 l 2. 78 06 3. 08 05 2. 05 3. 04 05 3. 04 06 2. 64 07 1. 78 05 2. 13 05 2. 5S O5 2. 49 05 2. 30 05 2. 2l 00 3. 20 05 2. 48 05 *=too low to measure.

The accompanying drawing illustrates the supersensitizing effect obtained with three of our new combinations of `dyes in gelatino-silverbromiodide emulsions. Each gure of the drawing is a diagrammatic reproduction of two, or in the case of Figure 1, three spectrographs. In each gure the sensitivity fof the emulsion containing the carbocyanine dye of Formula I or Ia, is represented by the solid lower curve. The upper curve represents the sensitivity conferred on the emulsion by the combination of the carbocyanine dye of Formula I ror Ia and the carbocyanine dye of Formula II. In Figures 2 and 3, the curve showing the sensitivity conferred on the emulsion by the carbocyanine dye of Formula II alone has been eliminated as it is identical with that of Curve A in Figure 1.

In Figure 1, curve A represents the sensitivity of an ordinary gelatine-silver-bromiodide emulsion sensitized With 5,5'dichloro1,1,3,3'tetra ethylbenzimidazolocarbocyanine iodide, curve B represents the sensitivity of the same emulsion containing 5,5-clichloro3,3,Q-triethylthiacarbocyanine bromide, and curve C represents the sensitivity of the same emulsion containing 5,5- dichloro l,1',3,3 tetraethylbenzimidazolocar bocyanine iodide and 5,5'-dich1oro-3,3,Q-triethylthiacarbocyanine bromide. The sensitometric measurements for these emulsions are given in Example 1 of the above table.

In Figure 2, curve D represents the sensitivity of an ordinary gelatinesilver-bromiodide emulsion sensitized with 3,3'-dimethyl9-pheny1 4,5,4,5-dibenzothiacarbocyanine bromide, and curve E represents the sensitivity of the same emulsion containing 3,3 dimethyl 9 phenyl- 4,5,4,5 -dibenzothiacarbocyanine bromide and 5,5',6,6 tetrachloro 1,1,3,3 tetraethylbenzimidazolocarbocyanine iodide. The sensitometric measurements for these emulsions are given in Example 28 in the above table.

In Figure 3, curve F represents the sensitivity of an ordinary gelatine-silver-bromiodide emulsion sensitized with 9-(3-indolyl)-3,3-din1ethy1 4,5,4,5 dibenzothiacarbocyanine iodide, and curve G represents the sensitivity of the same emulsion containing 9- (B-indolyl) 3,3-dimethy1 4,5,4',5 dibenzothiacarbocyanine iodide and 5,5,6,6.- tetrachloro 1,1,3,3' tetraethylbenzimidazolocarbocyanine iodide. The sensitometric measurements for these emulsions are given in Example 26 of the above table.

Our invention is primarily directed to the ordinarily employed gelatino-silver-halide developing-out emulsions, e. g. gelatine-silver-chloride, -ohlorobromide, chloroiodide, -ch1orobromiodide,

-bromide and -bromiodide developing-out emusions. While the results in the above table were used alone, does not appreciably increase the speed of the combination with dye (b).

TABLE A Minus Coating g. dye/mole Dye Green Gamma Blue Gamma Fog of AglBr Speed Speed dye (e) 14.8 2. 24 41.0 2. 34 .03

dye (b) 31. 0 2. 18 47. 0 2. 40 05 dye (l1) (0 80)-i-dye (e) 53. 0 2. 06 94. 0 2. 40 05 dye (b) (0.080)+dye (e) (0.040). 69.0 1.92 130.0 2. .05

dye (b) (0.080)Idye (e) (0080)..." 65.0 1.90 150.0 2.02 .05

In each ofthe above tables the speed figures are l0/i.

obtained using gelatino-silver-bromiodide emulsions, excellent results have also been obtained using gelatino-silver-chlorobromide emulsions. Emulsions which form the latent image mostly inside the silver halide grains, such as the emulsions set forth in U. S. Patent 2,456,956, dated December 2l, 1948, can also be employed in practicing our invention.

The emulsions prepared in accordance with our invention can be coated in the usual manner on any suitable support, e. g. glass, cellulose nitrate iilm, cellulose acetate film, polyvinylacetal resin rllm, paper or metal.

Photographic silver halide emulsions, such aS those listed above, containing the supersensitizing combinations of our invention can also` contain such addenda as chemical sensitizers, e. g. sulfur sensitizers (e. g. allyl thiocarbamide, thiourea, allylisothiocyanate, cystine, etc), various gold compounds (e. g. potassium chloroaurate, auric trichloride, etc.) (see U. S. Patents 2,540,- 085; 2,597,856 and 2,597,915), Various palladium compounds, such as palladium chloride (U. S. 2,540,086), potassium chloropalladate (U. S. 2,598,079), etc., or mixtures of such sensitizers; antifoggants, such as ammonium chloroplatinate (U. S. 2,566,245), ammonium chloroplatinite (U. S. 2,566,203), benzotriazole, nitrobenzimidazole, -nitroindazole, benzidine, mercaptans, etc. see Mees-The Theory of the Photographic Process, Macmillan Pub., page 460), or mixtures thereof; hardeners, such as formaldehyde (U. S. 1,763,533), chrome alum (U. S. 1,763,533), glyoxal (U. S. 1,870,354), dibromacrolein (Br. 406,750), etc.; color couplers, such as those described in U. S. Patent 2,423,730, Spence and Carroll U. S. application 771,330, led August 29, 1947, etc.; or mixtures of such addenda. Dispersing agents for color couplers, such as those set forth in U. S. Patents 2,322,027 and 2,304,940, can also be employed in the above-described emulsions.

In the above table it will be noted that in certain examples the amounts of dyes used in the supersenstizing combinations do not correspond to the amounts used with each dye alone. Actually, supersensitization occurs according to our invention when the combination of dyes gives more speed than either dye alone at any concentration. Thus, in some instances, the amount of dye, when used alone, is not identical with that used in the super ensitizing combination. This is due to the fact that optimum conditions have been used, insofar as possible, in each of the coatings. Use of larger amounts ci' dyes in the supersensitizing combinations is not necessary, and in some instances, is actually detrimental. This is illustrated in the following table where it is evident that use of larger amounts of dye (e) in the supersensitizing combination, more than half that required for optimum sensitizing by dye (e) wherein R., R3, R4, Z, Z2 and X each have the values given above, with a cyclammonium quaternary salt selected from those represented by the following general formula:

IV /Z\ l Ri-l-C-D wherein Rl, X1, and Z each have the 'values given above, and D represents an electro-negative group, such as an alkylmercapto group, an arylmercapto group, e. g.:

wherein R7 represents an alkyl or an aryl group, e. g. methyl, ethyl, phenyl, o, m, and p-tolyl, etc., or a -arylaminovinyl group, e. g.:

wherein ,Ra represents an acyl group, such as acetyl, propionyl, benzoyl, etc., or a hydrogen atom, and R9 represents an aryl group, e. g. phenyl, o, 111-, and p-tolyl, etc.

The condensation of the compounds representedby Formula III with the compounds of Formula IV can advantageously be accelerated by heating, e. g. the temperatures varying from room temperature (about 20 C.) to 100 C., 0r to the reflux temperature of the reaction medium. Inert solvents, such as the aliphatic alcohols, e. g. ethanol, n-propanol, n-butanol, etc., 1,4-dioxalne, pyridine, etc., can be used. Basic condensing agents can also be employed to advantage. Typical basic condensing agents comprise the trialkylamines (e. g. triethylamine, tri-n-butylamine,

Vn-propylamine, triisoamyl amine, etc), the N,N

dialkylanilines (e. g. N,Ndimethylah.iline, N,N-

diethylaniline, etc), the Nalkylpiperidines (e. g. Nmethylpip.eridine, N-ethylpiperidine, etc.) etc.

The intermediates represented by Formula III can advantageously be prepared by condensing a cyclammonium quaternary salt selected from those represented by the following general formula:

. wherein R, X' and Z each have the values given above, together with an alkyl orthoacetate selected from those represented by the following general formula:

VI CH3-(XORG:

wherein R represents an alkyl group, such as methyl', ethyl, etc., and a compound selected from those represented by the following general formula:

VII

wherein R3, R4, and Z2 each have the values given above. The intermediates represented by Formula III above are. new. The intermediates of Formula IV wherein D represents a -arylaminovinyl group have been previously described in the art (see, for example, British Patent 344,409, accepted March 4J 1931). The intermediates of Formula IV wherein D represents an electronegative group are also known (see, for example, British Patent 424,559, accepted February I18, 1935.). The intermediates of Formulas V, VI, and VII have also been previously described in the art (for example, those of Formula V in U. S. Patent 2,537,880, issued January 9, 1951, those of Formula VI in U. S. Patent 1,994,563, issued March 19, 1935, and those of Formula VII in British Patent 529,440, accepted November 21, 1940).

The following examples will serve tov illustrate the manner of preparing a number of the dyes embraced by Formula Ia above.

Example 44 .-9- (1 -etlLyZ-Z,5-dimethyl-3-pyryl) 3,3dimethylthiacarbocyanine iodide 1 ethyl 2,3',5,6 tetramethyl 3 pyrrolothiacarbocyanine iodide (1.09 grams, 1 mol.) and 3 methyl 2 methylmercaptobenzothiazolium p toluenesulfonate (0.92 gram, l mol.) were dissolved in ethyl alcohol ml.) of triethylamine (0.5 ml., 2 mol.) was added. The reaction mixture was heated under reflux for ten minutes and the crude dye precipitated bythe addition of water (100 ml.). The crude dye was filtered olf, dried and then` recrystallized from methyl alcohol; after two recrystallizations the \o,=oH-C=oH-o -CH II N C-CHa 02H5 I I da 2,3',5,6 tetramethyl l phenyl 4,5' benzo 3 pyrrolothacarbocyanine iodide (0.83 gram, 1 mol.) and l-methyl-2-methylmercaptonaphtho 1,2 thiazolium p toluenesulfonate (1.04 grams, 1 mol.+70% excess) and triethylamine (1.0 ml., 1 mol.l300% excess) were reuxed in ethyl alcohol (10 ml.) for one hour. The reaction mixture was chilled and filtered and the crude dye washed with Water, methyl alcohol, and acetone, and dried. The yield of purified dye after two recrystallizations from methyl alcohol was 53%; M. P. 217-18 C. dec.

Example 46. 3,3' dieth'yz 9 3 indozyz) 4,5,4',5 -dibenzoselenathiacdrbocyanine iodide 3 -ethyl 8 methyl 4,5' benzo 3 indolothiacarbocyanine iodide (0.50 gram, 1 mol), 1 ethyl 2 ethylmercaptonaphtho [1,2] selenazolium ethosulfate (0.90 gram, 1 mol.+l00% excess). and triethylamine (0.6 ml., 1 mol.+300% excess)V wereV reuxed in ethyl alcohol (10 ml.) for one hour. The reaction mixture was ltered hot andi the product was thoroughly washed with methyl alcohol and dried. The yield of puried dye was 59% after twov recrystallizations from cresol and. methyl alcohol; M. P. 281%2c C. dec.

- S O2-CuH4-CHs(p) 2,3,8 trimethyl 4",5,6,7 dibenzo 3 -indolothiacarbocyanine p-toluenesulfonate (0.59 g., mol), I-methyI-Z-methylmercaptonaphtho [1,2] thiazolium p-toluenesulfonate (0.63 g., 1 mol-i- 50%) and triethylamine (0.7` ml., l mol.+400%) were refluxed in ethyl alcohol (20 ml.) for one hour. The reaction mixture was filtered hot and the crude dye thoroughly washed with water, acetone and alcohol and then dried. After two recrystallizations from methyl alcohol the yield ofpuried dye was 0.60` g. (76%); M. P. 272-3 dec.

In a manner similar to that illustrated in Examples 44-4'7 above, the following dyes embraced by Formula Ia above were prepared:

Dye

Yield, percent 3,3dimethyl-9-(2methy1-3-indolyl)oxathiacarbocyanine iodide The following examples will serve to illustrate more fully the manner whereby the new intermediates represented by Formula III above can be prepared.

Example 48.-1,3-diethyl-Z,5,6-trimethyl-B-pyrrolothiacarbocyanine perchlorate 3ethyl-2-methylbenzothiazolium p-toluenesulfonate (34.9 grams, 1 mol.), 1-ethyl2,5dimethyl pyrrole (14.6 grams, 1 mobi-10 percent excess) and ethyl orthoacetate (24.3 grams, 1 mol.-|200 percent excess) were refluxed in ethyl alcohol ml.) for 4 hours. The reaction mixture was chilled and treated with aqueous sodium iodide (2O grams in 150 m1,). The solidwhich separated was filtered oiT and discarded. The filtrate was treated with an additional 400 ml. of water and chilled overnight. The product which separated was filtered off, washed with acetone and dried.

25 Washed with acetone and dried. After two recrystallizations from methyl alcohol (and filtered through decolorizing carbon) the yield of pure dye was 2%; M. P. 192-3 C. dec.

Example 50.-2,3,8 trimethyl-4,5,6,7dibenzo B-indolothiacarbocyanine p-toluenesulfonate 1,2 dimethylnaphtho-[1,2lthiazolium p-toluenesulfonate (19.3 g., 1 mol.), 2-methyl-6,7ben zindole (9 g., 1 mol.) and ethyl orthoacetate (16 g., 1 mol.+ 100%) were reuxed in acetic anhy.- dride (40 ml.) for one hour. The reaction mixture was then poured into warm water (400 m1.)

After conversion to the perchlorate and two reand allowed to Stand mm1 the aceuc anhydnde crystallizations from methyl alcohol (and ltered had deonflposed' Ethel: (400 m11) was then added through decolorzing carbon) the yield of pure Wlth surrmg and the mlxtulfe ahmed ltered E md dye was 4,5 percent; melting point 1880490., C the crude product washed with acetone and dried. Anazyss. ca1cu1ated for C20H25C1N204S: C, The yield of dye after recrystallization from 56.54; H, 5.93. Found: C, 56.9; I-I, 6.7. nthyl alcohol was 1.25 g. (4%); M. P. 179180 e Example 49.-2,3',5,6' feamfhZ/l 1 Phelllll- What we claim as our invention and desire se- 4,5'-1187120-3-lOi/TTOlOthcarbOciI/amne iodidey cured by Letters Patent of the United States is:

S 1. A photographic silver halide emulsion sensi- CH3 60 tized with a supersensitizing combination of at C CH= C 0H least one carbocyanine dye selected from those H3C (||J (nl OH represented by the following general formula: N l C: \I ,/Z\`\ //Z1\`\ H5 65 R-N C=CHC=CH0 ily-R1 1,2-dimethylnaphtho 1,2-thiazolium p-toluene- 2 X sulfonate (38.5 grams, 1 m01.), 2,5-dmethy1-1- wherein R and Ri each represents an alkyl group, phenylpylrole (20 grams.' 1 mo1.+10% excess) R2 represents a member selected from the group and @thi/101111030619515@ (25.0 grams, 1 m01|20% 70 consisting of an alkyl group, an aryl group, and

excess) were refluxed in ethyl alcohol for three hours and then treated with sodium iodide (20 grams) in water (400 ml.) and chilled overnight. The aqueous solution was decanted and the residue washed with water and ether and finally a pyrryl group, Z and Z1 each represents the nonmetallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, and X represents an acid radical, and at least one carbocyanine dye4 se- 15 lected, from thoseV represented by the; following general formula.:

wherein Rs and Rs each represents an alkyl group,

l l R-N wherein R and R1 each represents an alkyl group, R2 represents a member selected from the group consisting of an alkyl group, an aryl group, and a pyrryl group, Z and Z1 each represents the nonmetallic atoms necessary to complete a heterocyclic-nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the benzoselenazole series, those of the naphthoselenazole series, and those of the quinoline series, and X represents an acidV radical, and at least one carbocyanine dye selected from those represented by the following general formula:

wherein R5 and Re each represents an alkyl group, n represents a positive integer of from 1 to 2, and X1 represents an acid radical.

3. A photographic gelatino-silver-halide developing-out emulsion sensitized with a supersensitizing combination of at least one carbocyanine dye selected' from those represented by the following general formula:

wherein R and R1 each represents an alkyl group,

R2 represents a member selected from the group consisting of an alkyl group, an aryl group, and a pyrryl group, Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group. consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the benzoselenazole series, those4 of, the

naphthoselenazole series, and those of the quinoline series, and X represents an acid radicahandY at least one carbocyanine dye selected from those represented by the following general formular:

whereinR5 and Rs each represents an. alkyl group, n represents apositive integer of from 1 to2, and X1 represents an acid radical.

4. A photographic gelatino-silver-halide devel'- oping-out emulsion sensitized by a supersensitizing combinationof at least one carbocyanine dye selected fromv those represented by the following generall formula wherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, R2 represents a member selected from the group consisting of a methyl group, an ethyl group, and a phenyl group, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the benzoselenazole series, those of the naphthoselenazole series, and those of the quinoline series, and at least one carbocyanine dye selected from those represented by the following general formula:

wherein R5 and Rs each represents a member selected from the group consisting of a methyl group, an ethyl groupand an allyl group, n represents a positive integer of from 1 to 2, and Xi represents an acid radical.

5. A photographic gelatino-silver-bromiodide developing-out emulsion sensitized by a supersensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, R2 represents a member selected from the group consisting of a methyl. group, an ethyl group, and a phenyl group, X represents an acid radical, and Z and,r Z1 each represents the non-metallic-atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of they benzothiazole series, those of the naphthothiazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the benzoselcnazoler series, those 0f the naphthoselenazole series, and .those of the quinoline series,

and atv least one carbocyanine dye selected` from 17 those represented by the following general formula:

R, Ilz

wherein R and R1 each represents a member selected from the group consisting of a methyl group and an ethyl group, R3 and R4 each represents a member selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, and a phenyl group and Ra and R4 together represent the non-metallic atoms necessary to complete a heterocyclic nucleus of the pyridine series, Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzotliiazole series, those of the naphthothiazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the benzoselenazole series, those of the naphthoselenazole series, and those of the quinoline series, Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the pyrrole series, and X represents an acid radical, and at least one carbocyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents a member selected from the group consisting of a methyl group and an ethyl group, R3 and R4 each represents a member selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, and a phenyl group and R3 and R4 together represent the non-metallic atoms necessary to complete a heterocyclic nucleus of the pyridine series, Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzo-Xazole series, those of the naphthoxazole series, those of the benzoselenazole series, those of the naphthoselenazole series, and those of the quinoline series, Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the pyrrole series, and X represents an acid radical, and at least one carbocyanine dye selected from those represented by the following general formula:

wherein R, R1 and R2 each represents an alkyl group containing from 1 to 2 carbon atoms, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series, and X represents an acid radical, and at least one carbocyanine dye selected from those represented by the following general formula:

wherein R5 and Re each represents a member selected from the group consisting of a methyl group, an ethyl group, and an allyl group, n represents a positive integer of from l to 2, and X1 represents an acid radical.

9. A photographic gelatino-silver-halide developing-out emulsion sensitized with a supersensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

wherein R, R1, and R2 each represents an alkyl group containing from 1 to 2 carbon atoms, Z

19 represents the non-metallic atoms lnecessary to complete a heterocyclic nucleus of .the benzoselenazole series, ,and X represents an acid radical, and at least one carbocyanine dye selected from those represented by the following general formula:

wherein R5 and Rs each represents a member selected from the group consisting of a methyl group, an ethyl group, and an allyl group, n represents a positive integer of from l to 2, and Xi represents an acid radical.

10. A photographic gelatno-silver-halide developing-out emulsion sensitized with a supersensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

wherein R, R1, and R2 each represents an alkyl group containing from 1 to 2 carbon atoms, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and X represents an acid radical, and at least one carbocyanine dye selected from those represented by the following general formula:

wherein R5 and Re :each represents a member .selected from the group consisting of a methyl group, an ethyl group, and an allyl group, .n represents a positive integer of from 1 to 2, and X1 represents an acid radical.

l1. A photographic gelatino-silver-halide de- `veloping-out emulsion sensitized with a supery sensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

I/Z`` R- =cH-c=CH- n al wherein IR, R1, and R2 each represents an alkyl group containing from 1 to 2 carbon atoms, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzoxazole series, and X represents an acid radical, and at least one carbocyanine dye selected from those represented by the following general formula:

N 1kg Xi wherein R5 and Re each represents a member selected from the group consisting of a methyl group, an ethyl group, and an allyl group, n representss a positive integer of from 1 to 2, `and X1 represents an acid radical.

12. A photographic gelatino-silver-halide developing-out emulsion sensitized with a supersensitizing combination of at least one carbocyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from 1 to 2 carbon atoms, Ra and R4 each represents a member selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, and a phenyl group, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzoindole series, and X represents an acid radical, and at least one carbocyanine -dye selected vfrom those represented by the following general formula:

wherein R5 and Re each represents a member selected fromv the group consisting of a methyl group, an ethyl group, and an allyl group, n represents a positive integer of from l to l2, and X1 represents an acid radical.

13. A photographic gelatino-.silver-halide developing-.out emulsion sensitized with a supersensitizing combination of 5,5'dichloro3,3,9 triethylthiacarbocyanine bromide and 5,5-

-dichloro 1,1,3,3 tetraethylbenzimidazolocarbocyanine iodide.

14. A photographic gelatine-silver-halide developing-out emulsion sensitized with a supersensitizing combination of 3,3diethyl-9methyl selenacarbocyanine iodide and 5,5,6,6tetra chloro `1,1,3,3 tetraethylbenzimidazolocarbo cyanine iodide.

15. A photographic gelatino-silver-halide developing-out emulsion sensitized with a supersensitizig combination of 3,3diethyl8methyl y4,5,4',5 -dibenzothiacar-bocyanine bromide and No references cited. 

1.A PHOTOGRAPHIC SILVER HALIDE EMULSION SENSITIZED WITH A SUPERSENSITIZING COMBINATION OF AT LEAST ONE CARBOCYANINE DYE SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 